Coupling for circulating coils



y 7, 1931- I A. FRIEDMAN 1,813,284

COUPLING FOR CIRCULATING COILS Filed Feb. 29, 1928 Patented July 7, 1931 1 1,s13,2sa

UNITED STATES PATENT OFFICE.

ARTHUR FRIEDMAN, OF CLEVELAND, OHIO, ASSIGNOR TO THE CLEVELAND HEATER COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO I COUPLING- FOR CIRCULATING COILS Application filed February 29, 1928. SerialNo. 257,917,

This invention relates to improvements in gas fired liquid heaters and in particular to the circulating coils for gas burning domestic water heaters.

5) It has for its object the provision of a water heater circulating coil that is inexpensive and easy to manufacture, and that is more durable than the ordinary type of circulating coils, and that is protected against 10. the destructive action of the condensation products of combustion'of the gaseous fuels used in gas burning water heaters.

My invention in general consists in the provision of an extending lip formed on the lower coupling and in contact with the under side of the lower portion ofthe heater coils,

for the purpose of collecting and evaporating the condensation products of combustion from the gas burner. v

The principal cause of failure in coils of this type is generally attributed to the presence of sulphuric acidin the water of condensation which collects on the coils and runs to their lowermost portion and there attacks the joint between the coils and the coupling.

In copper water heater coils of the ordinary type, there is a decided tendency to failure at the point of the coils where they enter the lower coupling member. The failure results from the disintegration of the copper, from which the coils are made. It is usually accompanied by the formation of copper sulphate at the point of failure of the coil. It is common knowledge that any commercial gases particularly manufactured gas, upon burning give off sulphur dioxide, as well as water vapor.

The accepted theory of the operation of this phenomena in water heaters is that the condensation of water vapor, which takes place on the heater coils, causes the formation of sulphurous acid by combining with the sulphur dioxide given oil by the burning as. 45 b As the weak sulphurous acid thus formed on the heater coils runs to the bottom of the coils, a certain amount of it is converted into sulphuric acid, by reason of coming in contact with What copper oxide may be present on the heater coils.

The acid solutions thus formed, collect at the lowermost point of the coils, which is Where they enter the coil coupling. At this point there is apt to be present considerable copper oxide if it is a brazed joint. The oxide referred to is present as a result of the action of the gas flame used in the brazing operation.

Furthermore, the copper tubing at the brazed joint is somewhat weakened, due to co the heat applied in brazing, whichcauses some oxidation as well as annealing, both of which are apt to leave this portion. of the copper tubing in a condition in which it is more susceptible to the corrosive action of as sulphuric action thanthe other portions of thetulbe. j

Disregarding for the moment, the type/of joint between the tubing and the coupling, whether it be a brazed jointor ajunion coupling, it is apparent that a part of the aforementioned liquids, condensed from the products of combustion of the gaseous fuel, come to iest at the junction of the coupling and the C015.

At this junctionpoint, which is in close proximity to the heater burner, the condensation products are further concentrated by directaction of the flange and evaporation of excess water in the acid solution produc ing concentrated sulphuric acid, which readilyicombineswith the copper of the heater co1 I It is upon this theory, which is supported by the presence of copper sulphate at the junction of the coupling and the tubing, after the heater has been in use for some time, that the common cause of failure of the f3oppercoils of water heaters is accounted The formation of scaleand liming of the interior of the heater coils accelerates their deterioration. Under these conditions, when in operation, the heater coils ar-e kept at a much higher degree of temperature, due to the low thermal conductivity of the fouled tubing, and in addition to being more rapidly H disintegrated bysulphuric acid, the coils are 1 also oxidized by the direct action of the burner flame.

The primary object of this invention is to prevent the accumulation of the harmful condensation products of combustion at the weakest part of the heater coil.

This result is accomplished in my imroved coil by the provision of a projecting lip which is ntegrally; formed on the lower coil coupling member and which serves as a means for collecting and diverting the con densed liquids on the coil away from the joint between the coil and the coupling.

This invention is particularly useful in water heaters in which the ends of the cir-= culating coils are brazed in the coil coupling member, as the coils are somewhat weakened by this operation, due tothe high heat which is applied to them andto the action of fluxes which are used in brazing.

In the accompanying drawings; Fig. 1, illustrates a front elevation partly in section of a Water heater constructed in accordance with and adapted for use in practicing my invention. Fig. 2, is a top elevation of the lower coupling member shown in Fig 1. Fig. 3, is a side elevation of the lower coupling member. Fig. 4, is an elevation showing the under side ofthe lower coupling member and Fig. 5, is a section taken on line 55 Fig. 3.

Referring to Fig. 1, the reference numeral 1, indicates the heater casing or jacket of a conventional gas fired domestic water heater. This casing provides a housing for the copper water circulating coils 2 which are adapted to be put into communication with a storage vessel or tank by means of the lower and upperunion-connections 8 and 4, respectively.-

Means for applying heat to the coils is providedfor by the gas burner. 5, which is mounted on an air and gas mixing tube 7, of the Venturi type. The burner 5 is positioned below, the coils in the lower portion of the heater jacket. A gas cock 8 is mounted at the inlet end of the mixing tube 7, and is adapted ,to be connected to a source of gas supply,

The lower ends of thecoils. 2 are adapted to be received in the coupling member 6. The usual method of securing the coils in this member is by brazing. A pair of outwardly extending tapered lips 9 form a part of the couplingcasting These lips extend for a short, distance along the underside of the.

heater coils 2 at the the coupling member. I The purpose and object of the lips 9 is to providea path for the liquids which are conpoint where they enter densed from the products, of combustionon the outside of the coil and which under the influence of gravityfind theirway to the lower coupling member. The lips 9 tend to direct the condensation products away: from. the brazed j ointbetween the coupling and the. coils and causethem to accumulate and drip y from ,the point 10 of thecouplingmember 6.

' j The corrosive action of whatever sulphuric acid may be present in the afore-mentioned liquids is directed against the thick and heavy wall of the coupling casting instead of on the thinner wall of the tubing 2. In this manner the life of the coils is greatly lengthened by protecting them at their weakest point from the corrosiveaction of the products of'combustion from the gas burners, which products condense and collect on the heater coils.

It is apparent that my improved heater coil could. be used in conjunction with oil burning water heaters as well as gas burning water heaters and that it could be used to advantage in the heating of liquids other than water, where said coils are subjected to treatment similar to that which they receive in gas tired water heaters.

Furthermore, it is to be understood that the particular forms of apparatus shown anddescribed, and that particular procedure set 5 forth, are presented for purposes of eXplana-- tion and illustration and that various modifications of said apparatus and procedure can"- be made without departing from my invention as defined in the appended claims: gar.

Having described my invention, I claim:

1. A gas fired water heatercomprising a I heater casing, a circulating coil housed in said casing, a lower coupling member receivsaid coil, means to apply heat to said coil, and means integrally formed on said lower i coupling member comprising an extendingportion 01'? decreasing thickness as its outer edge is approached and adapted for contact with said coil to direct the flow of the con densed products of combustion deposited on said coil. from the joint between said 'coupling member and said coil.

2. In a gasfired water heater, water circulating coils, a lower couplingmembercon-- nected to the corresponding ends ofsaid'coils, anda pair of tapered projecting lips integraL' 1y formed on said coupling member extending along and in contact with the under sides'of said coils. v I

3. A coupling member for a water'heat'er coil comprising, a single casting-h'aving an" opening receiving an end of the coil and hav ing formed thereon a narrow tapered exten sion contiguous to said opening adapted to 1-15 

